Merge pull request #1139 from input-output-hk/gen-hydra-key-should-not-overwrite

gen-hydra-key should not overwrite key if it exists

Author: Arnaud Bailly

CHANGELOG.md

@@ -10,6 +10,9 @@ changes.
 
 ## [0.14.0] - UNRELEASED
 
+- Improved `gen-hydra-keys` command to not overwrite keys if they are present
+  already.
+
 - Hydra node API `submit-transaction` endpoint now accepts three types of
   encoding: Base16 encoded CBOR string, TextEnvelope type and JSON.
 

hydra-node/src/Hydra/Utils.hs

@@ -1,15 +1,26 @@
 module Hydra.Utils where
 
 import Crypto.Random (getRandomBytes)
-import Hydra.Cardano.Api (File (..), FileError, Key (SigningKey), getVerificationKey, writeFileTextEnvelope)
+import GHC.IO.Exception (userError)
+import Hydra.Cardano.Api (File (..), FileError (FileIOError), Key (SigningKey), getVerificationKey, writeFileTextEnvelope)
 import Hydra.Crypto (HydraKey, generateSigningKey)
 import Hydra.Options (GenerateKeyPair (..))
 import Hydra.Prelude
+import System.Directory (doesFileExist)
 import System.FilePath ((<.>))
 
 genHydraKeys :: GenerateKeyPair -> IO (Either (FileError ()) ())
 genHydraKeys GenerateKeyPair{outputFile} = do
-  sk :: SigningKey HydraKey <- generateSigningKey <$> getRandomBytes 16
-  runExceptT $ do
-    ExceptT $ writeFileTextEnvelope (File (outputFile <.> "sk")) Nothing sk
-    ExceptT $ writeFileTextEnvelope (File (outputFile <.> "vk")) Nothing (getVerificationKey sk)
+  fileExists <- doesFileExist outputFile
+  if fileExists
+    then
+      pure $
+        Left $
+          FileIOError
+            outputFile
+            (userError "File already exists! Please remove it in order to generate new hydra keys.")
+    else do
+      sk :: SigningKey HydraKey <- generateSigningKey <$> getRandomBytes 16
+      runExceptT $ do
+        ExceptT $ writeFileTextEnvelope (File (outputFile <.> "sk")) Nothing sk
+        ExceptT $ writeFileTextEnvelope (File (outputFile <.> "vk")) Nothing (getVerificationKey sk)

hydra-node/test/Hydra/UtilsSpec.hs

@@ -4,6 +4,7 @@ import Hydra.Cardano.Api (FileError)
 import Hydra.Options (GenerateKeyPair (GenerateKeyPair))
 import Hydra.Prelude
 import Hydra.Utils (genHydraKeys)
+import System.FilePath ((</>))
 import Test.Hydra.Prelude
 
 spec :: Spec
@@ -13,3 +14,11 @@ spec = do
     case result of
       Left (_ :: FileError e) -> pure ()
       Right _ -> expectationFailure "getHydraKeys should have failed with FileError"
+
+  it "Should throw if the file already exists" $
+    withTempDir "gen-hydra-keys" $ \tmp -> do
+      writeFile (tmp </> "hydra") "hydra key"
+      result <- genHydraKeys (GenerateKeyPair $ tmp </> "hydra")
+      case result of
+        Left (_ :: FileError e) -> pure ()
+        Right _ -> expectationFailure "getHydraKeys should have failed with FileError"